Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$233.45	3.309%	$241.1749	$241.17	$241.15	$241.20
Purchase #2	$7.43	6.617%	$7.9216	$7.92	$7.90	$7.90
Purchase #3	$233.77	3.751%	$242.5387	$242.54	$242.55	$242.50
Purchase #4	$209.55	11.145%	$232.9043	$232.90	$232.90	$232.90
Purchase #5	$94.39	4.246%	$98.3978	$98.40	$98.40	$98.40
Purchase #6	$187.64	4.393%	$195.883	$195.88	$195.90	$195.90
Purchase #7	$62.27	7.589%	$66.9957	$67.00	$67.00	$67.00
7 purchase totals =	$1,028.50		$1,085.8160	$1,085.81	$1,085.80	$1,085.80